Radiogoniometer



Feb. 3, 1942. c. s. COCKERELL 2,271,517

RADIOGONIQMETER Filed Jan. 27, 1940 Christophe) (51222 7118 3211;

Patented Feb. 3, 1942 UNITED ST RADIOGONIOMETER Christopher Sydney Cockerell, Danbury, England, assignor to Radio Corporation of America, a

corporation of Delaware Application January 27, 1940, Serial No. 315,927 In GreatBritain January 28, 1939 9 Claims.

This invention relates to radiogoniometers and has for its main object to provide improved goniometers in which capacity coupling between the field coils and the search coil may be reduced without resorting to the use of screening.

Another object of the invention is to provide a method of winding a radiogoniometer such that the search coil thereof may be earthed at one end.

A further object of the invention is to reduce the production of high harmonic errors in short Wave radiogoniometers having only a few turns.

It is known to reduce capacity coupling between the field coils and search coil of a radiogoniometer by interposing an electrostatic screen between the two sets of coils, but this expedient has the disadvantages that losses are introduced by the screening, that there is an increase in self-capacity of the radiogoniometer due to the screening, and that the presence of the screening results in a decrease in the coupling coefficient by reason of the space it occupies.

According to this invention, the search coil of a radiogoniometer or each of the field coils thereof is so constructed that the turns thereof are of substantially the same size and shape, each turn in the coil or coils in question having an axis of symmetry which is common to all the others. To put the matter in another Way, the invention may be regarded as consisting in so winding either the search coil or each field coil that all the turns of the coil or coils in question arewound on great circles. The term great circles is used in an analogy to a great circle of the earth and, as will be seen later, it is used in a rather wide and, strictly speaking, inaccurate sense in that the turns need not be circular. Each turn in question is, however, either itself a great circle or is symmetrical with respect to a great circle.

The invention is illustrated in and further explained in connection with the accompanying drawing, in which Fig. 1 is a simplified schematic view of an embodiment of this invention; Fig. 2 is a perspective view of an embodiment of the invention; Fig. 3 is a schematic view of a modification of this invention; Fig. 4 is similar to Fig. 2, but shows a pair of coils; Fig. 5 is a search coil of the type known in the prior art; Fig. 6 is a graph illustrating the distribution of flux in a goniometer; Fig. 7 is still another modification of this invention; Fig. 8 is a cross-sectional view of a'goniometer embodying a field coil wound in accordance with this invention; and Fig. 9

a search coil wound in accordance with the present invention.

Referring to Fig. 1, this represents in simplifled schematic view one form of search coil in accordance with this invention for use in a radiogoniometer with field coils of ordinary construction. For the sake of simplicity, the coil former is represented merely by two discs I and 2 and the axis of rotation by the dotted line 3, 4. The coil itself is composed of wire W and the direction of winding is clearly indicated by the arrow heads on the wire. The two ends of the winding are marked El and E2 in this figure. As will be apparent from the figure, the turns of the search coil are of substantially the same size and shape, and have a common axis of symmetry passing through the points QQ. In this figure, only two turns of the coil are shown for the sake of simplicity in drawing. The general appearance of the coil is better shown in Fig. 2 where more turns are indicated. It will be noted that adjacent turns of the windings W lie in different planes which intersect along the axis of symmetry Q-Q, which is perpendicular to the axis of rotation.

Fig. 3 shows another form of search coil in accordance with this invention, this search coil being of cylindrical nature and again suitable for use in conjunction with an ordinary known field coil system. The axis of rotation is represented by the dotted line 3, 4, and the former by end discs I, 2'. W is the wire and, as before, the direction of winding is indicated by arrow heads thereon. In this case, the common axis of symmetry of the turns is, in effect, the pivotal axis.

Fig. 4 shows a pair of field coils wound in 1 accordance with this invention and for use in is a sectional view of a goniometer embodying a radiogoniometer having a search coil wound in the usual way. As will be obvious, each of the field coils comprises two sections-these are marked Fl FZ-and they are wound in the same way as the search coil of Figs. 1 and 2. For purposes of comparison, an ordinary search coil wound in the at present usual manner and suitable for use in a radiogoniometer having a field coil system, as shown in Fig. 4, is represented in Fig. 5. It will be noted that the turns of this search coil do not have a common axis of symmetry, since each turn lies wholly on one side or the other of the axis 3, 4.

High harmonic errors are a common experience in known radiogoniometers, such errors being due to the irregular nature of the stator field brought about by the splitting of each stator Winding into two halves and, in short and ultrashort wave radiogoniometers, by the small number of turns that can be used. The nature of the formation of high harmonic errors will be better understood from the schematic representation of Fig. 6, in which the dots represent, in section, the stator or field coil turns, and the coils S represent the two halves of the usual form of search coil. The fiux lines are indicated conventionally by the curved lines. As will be apparent from Fig. 6, a slight rotation of the rotor (search coil) in either direction from the position shown will decrease the flux linkage with the stator field and, in this manner, harmonic errors are produced. This defect-can be greatly reduced in carrying out the present invention by distributing each of the turns of the coil or coils made in accordance with this invention,

i. e., by arranging the turns to cross one another at several places.

Fig. '7 shows a search coil of the general na-' ture of the search coil represented in Fig. 1 but with the turns distributed so as to minimize harmonicerrors. The expedient of distributing the turns may, of, course, be applied in similar fashion to field coils, in a case in which this invention is applied to the field coils instead of to the search coil.

Fig. 8 is a sectional view of a complete goniometer having fixed field coils Fl and F2, of the type illustrated in Fig. 4, and a search coil rotatably mounted within the field coil. The search coil has a pair of windings W, W, and is of the type illustrated in Fig. 5.

Fig. 9 is a sectional view of a complete goniometer having a conventional fixed field coil comprising the two perpendicular Windings F3 and F4 wound on the outer side of a cylindrical Winding form, for example, and a search coil 5 of the type illustrated in Fig. 2, having two crossed windings wound on forms I, 2, each turn of the conductor lying in a different plane which is at an angle to the plane of every other turn in the same section of the winding, the turns being symmetrical with respect to a common axis defined by the intersection of the planes of the field coils, that is, the axis of rotation,XX.

I claim as my invention:

1. A goniometer having a field coil and a rotatable search coil at least one of said coils comprising a plurality of turns of conductor, said turns all being of substantially the same size and shape and having a common axis of symmetry perpendicular to the axis of rotation.

2. A goniometer field coil system comprising a pair of field coils mounted in mutually perpen-. dicular planes, each of said coils comprising a rality of turns of substantially the same size and shape and having a common axis of symmetry A perpendicular to the axis of rotation of said field coil.

4. A goniorneter search coil comprising a plurality of turns of conductor, said turns each being of substantially the same size and shape and having a common axis of symmetry perpendicular to the axis of rotation of said search coil.

5. A goniometer search coil comprising a plurality of turns of conductor, said turns each having substantially the same size and shape and lying in a different plane but having a common axis of symmetry perpendicular to the axis of rotation of said search coil. I

6. A goniometer comprising a pair of field coils mounted in mutually perpendicular and intersecting planes anda rotatable search coil mounted within said field coils, said search coil comprising a plurality of conductors, each of said conductors lying in a different planeand being symmetrical about a common axis of symmetrywhich is defined by the intersection of said planes.

'7. A goniometer having a field coil and a search coil, said search coil having an axis of rotation, atleast one of said coils comprising a plurality of turns of conductor lying in difierent planes through a common axis of symmetry perpendicular to the axis of rotation of said search coil and having substantially the same shape and size.

8. A goniometer having a fixed field coil and a search coil mounted for rotation about an axis, at least one of said coils comprising a plurality of turns of conductor lying in respectively different planes which intersect along a common axisof symmetry perpendicular to saidaxis of rotation. v i v v 9. A goniometer having a fixed field coil and a search coil mounted for rotation about an axis, one of said coils comprising a plurality of turns of conductor lying in respectively different planes which intersect along an axis, of symmetry perpendicular to; said axis of rotation, substantially halfof said turns lying on each side of said axis of; rotation.

. CHRISTOPHER SYDNEY COCKERELL. 

